System L-374 was located in the Alpha Quadrant now inside Federation space. When the system was first discovered it lay beyond the edge of federation space by a considerable margin. It was reasonably close to the Klingon Empire. it was the second known system to be destroyed by the Doomsday Machine. The first was System L-370, which was nearby.
The system was partially destroyed by the Doomsday Machine around stardate 4202.3. The system had originally consisted of five planets. Upon the arrival of the USS Constitution NCC-1071]] the fifth planet had been destroyed, the first three planets were intact and the fourth planet was in the process of breaking up. The cause of that break up was the presence of the Doomsday Machine.
Further degradation of the system was prevented when the USS Enterprise NCC-1701 managed to disable the device.
That however was not the end of the story.
In 2407, an Orion starship located the device and purposefully reactivated it thinking that they were capable of controlling it. They were mistaken and the device turned against them and resumed it's destruction of the system.
The USS Boudicca responding to the Orion Syndicate ship's distress call then encountered the device. They were able to destroy the device, but not before it managed to destroy the last planet in the system for fuel. The system now consists of nothing but a mass of planetary debris circling it's primary star.